Humans weren't the first animals in space.
Prior to the launch of mankind in helmeted spacesuits, a number of animals orbited earth. Scientists were unsure how the human body would respond to weightlessness, or if it could even survive.
So a number of "guinea pig" test subjects--including actual guinea pigs--found themselves peering down from the solar system as early as the 1940s, catching more than a dozen sunsets in a day.
While humans are still learning to reach for the stars, it seems these animals were well on their way to touching the future. Like the 1986 Challenger and 2003 Columbia astronauts, many of these pets risked their lives for the sake of knowledge and discovery. It seems we have many different species of heroes to thank for space exploration.
What are some of these pet astronauts?
Canines made numerous debuts in space prior to the human astronaut. The most famous individual was Laika, a Russian stray plucked from the streets of Moscow for what was an inevitable suicide mission, as the return flight to Earth had not yet been programmed.
Cats have purred their way through the atmosphere starting with the French feline Felicette (often mistakenly called Felix). The cat was ejected in a successful parachute descent back to land in 1963.
Mice don't just don lab coats; they wear spacesuits, too. Four black mice went into space in 1959 aboard Discoverer 3.
According to NASA, they were the only animal payload on a Discoverer flight.
4. Russian Tortoises
Accompanying a human mannequin aboard the Soviet Union's Zond 5 in 1968, two Russian tortoises orbited the moon.
Despite technical failure, the reptiles were recovered in the floating orbiter in the Indian Ocean. They reportedly were down 10 percent in body weight and had some altered body chemistry but otherwise acted normally.
5. Guinea Pigs
China also sent a number of squeakers into space on an animal mission in 1990.
Rodents seem to be astronaut veterans. Rats have looked down at us from above a number of times.
Pregnant rats were also subjected to zero gravity conditions to monitor how the babies were affected.
These mischievous furballs have joined their other rodent friends in a handful of missions alongside mice, rats, and guinea pigs.
The first lagomorph on a rocket was Marfusha (meaning "Little Marsha"), companion to two dogs on a 1959 Russian mission. The three furry friends returned safely back to earth.
Ten newts flew through space in 1985. Due to their self-healing body part regeneration after injuries, these newts were manipulated with deformities and their regenerative capabilities studied in outer space.
How does a frog handle the vomit comet? Check out the clip above for a sampling of frogs in zero-g.
NASA sent two bullfrogs into space in 1970 as part of the Orbiting Frog Otolith program. (An otolith is an inner ear bone used to maintain balance.) Scientists got the data they were looking for, but the orbiter was not recovered.
Is swimming through water the same in space? A pair of mummichogs got a chance to find out as the first fish in space in 1973, also in a study of otoliths.
Japan sent an aquarium of medaka fish to the International Space Station in 2012. The transparent skin of this species allowed researchers to visually observe the effects of space on organs. Inside the tank, weightlessness caused the fish to swim in loops.
Without these pet astronauts, we would still have much to learn about space today. Two decades before man landed on the moon, animals were already experts at soaring through the Milky Way.